Earlier this month, Mazda announced plans to put a revolutionary Homogenous Charge Compression Ignition (HCCI) gas engine into production by 2019. Dubbed Skyactiv-X, this engine won't use its spark plugs at low loads, instead relying on compression for ignition, just like a diesel. It might not be the only next-level thing Mazda is working on, though.
A patent application just published on the US Patent and Trademark Office (USPTO) website shows an engine that uses two turbochargers and an electric supercharger. Both the schematic (Fig. 1) and drawing (Fig. 4) below show a gas-powered engine with two exhaust-driven turbochargers (11 and 15) operating in parallel with a single supercharger driven by electricity.
Text in the application says the electric supercharger would be used to provide low-end power while the two exhaust-driven turbos spool up. This is similar in concept to a 2.0-liter four-cylinder engine developed by Volvo that makes 450 hp in prototype form. Our Máté Petrány tested this engine back in his Jalopnik days, which you can .
The Volvo engine used a 48-volt electrical system to spin up its supercharger, but Mazda could use something different to build supercharger boost pressure. Friend-of-the-site and Truth About Cars contributor Bozi Tatarevic told me over Twitter DM that it's possible that this electric supercharger could run off .
Available in the Mazda 6 sedan, i-Eloop recovers heat energy from braking, turning into electricity stored in a supercapacitor that sends power to the car's various accessories. As we've noted before, it's possible for this supercapacitor to power a supercharger instead of, say, the air/conditioning.
What's also interesting about this patent application is that it shows this engine in a rear-wheel drive application. If you're a frequent reader of this website, we probably don't need to remind you that Mazda only has one rear-drive car on sale currently, the brilliant MX-5 Miata.
This doesn't mean that the next Miata will be a triple-charged monster. It's possible that this engine design might never see production at all, let alone in a Miata. And right now, it's unclear if this patent is related to the Skyactiv-X engine, though the company did confirm that this motor will be supercharged.
Regardless of what happens to this engine concept, it's incredibly cool. Leave it to Mazda to keep pushing the envelope on internal combustion.
Update 8/10/17 12:05 p.m. ET: Tatarevic just sent us an additional Mazda patent application which seems to describe this engine or a similar unit as being diesel powered. So, what is Mazda developing here?